The “Ice Bucket Challenge” has lit social media on fire, raising both money and awareness for amyotrophic lateral sclerosis, commonly known as Lou Gehrig’s disease. About 30,000 Americans now have the disease, which attacks nerve cells and ultimately leads to total paralysis, though the mind remains sharp. Life expectancy is typically two to five years from the time of diagnosis.

The stunt goes like this: People make a video of themselves dumping a bucket of ice water on their heads, post it on Facebook, Instagram or other social media sites, and then challenge friends to do the same within 24 hours or donate $100 to ALS. (Many do both.)